The fabrication and optical characterisation of SnO2 cluster films



SnO2 nano-clusters have been produced using a low temperature oxidation process. Tin clusters with a diameter of 7 nm were oxidised by heating in air at 250 °C for 24 hours. The oxidised clusters were studied using transmission electron microscopy (TEM), showing that the clusters do not coalescence or change their size significantly. The optical transmission of 50 nm thick SnO2 cluster films is greater than 90% from 800 nm to 380 nm and shows strong absorption for λ < 380 nm. The photoconductivity was characterised by a large peak at 3.9 eV with a smaller peak at 3.5 eV. Persistent photoconductivity is observed with long characteristic times and a strong dependence on the ambient atmosphere during the measurement. This was attributed to carrier production due to photo-induced desorption of oxygen from the surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)